(Newser)
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A spacecraft studying the planet Mercury has discovered evidence of enormous volcanic eruptions. The scale of the volcanic activity has astonished scientists, according to the National Geographic News. Images from the Messenger spacecraft reveal 3,600 cubic miles of solid lava inside a single crater—enough to drown the entire Baltimore/Washington metropolitan region under lava 12 times the height of the Washington Monument.

Mercury is only a tenth of the size of earth. "That's an awful lot of volcanic material in one place for such a little planet," said a mission co-investigator. Scientists believe the volcanic activity occurred some 4 billion years ago.